This invention relates to small connector receptacles in the form of miniature metal shells which are intended for insertion in openings of printed circuit boards, and more particularly to such receptacles wherein there are friction contact means adapted to co-act with contact pins of cooperable male connectors.
Heretofore various types of connector receptacles of the above kind have been proposed and produced. Commonly these have generally comprised tubular metal shells or cups in which spring contactors are disposed for engagement with the contact pins of cooperable connectors. The tubular shells or cups are inserted in openings of printed circuit boards with a sliding fit, and their walls are variously formed or embossed to effect a retention of the cup in the board after its insertion. Some cups are knurled for this purpose, others are formed with a non-circular cross section, and various diverse configurations have been employed in the past during the fabrication of the shell or cup, by modification of its wall to effect the retention.
In one prior construction the inner spring contactor was provided with resilient fingers which folded down alongside the outer shell or cup for the purpose of yieldably engaging the walls of the opening in the circuit board, to effect the retention. However, this construction had a drawback inasmuch as during the wave soldering of the connector, it sometimes happened that the solder would travel along the spring fingers and into the inner spring contactor. This would impair the resilience of the contactor and sometimes rendering it inoperative as a consequence.
Mainly the objective in the past has been to maintain the cost of the receptacles at a very low, acceptable figure inasmuch as large numbers of these components are utilized in various types of assemblies, where they constitute only a very small percentage of the overall unit.
Many prior receptacle shells or cups have not been fully satisfactory for the reason that they required strictly held tolerances of the opening or hole diameters in the circuit boards, and it was difficult or else undesirable to maintain such precise measurements of the openings. In consequence, it was found that the shells or cups would be only loosely held and not sufficiently secure, or else that they had too tight a fit, in which case it interfered with the easy insertion and also the subsequent operation. Some shells would become distorted where the openings in the circuit board were too small, and this altered the proper functioning of the spring contactor which was disposed in the shell.
In general, the prior working or forming of the shell wall to effect a retention was found to be unacceptable, also for the reason that it tended to restrict its use in some cases. At the same time, the forming of the shell walls in special shapes had to be critically considered because it was necessary to avoid an increase in the cost of the receptacle shells, since this would undesirably affect the cost of the assemblies where the shells were utilized.